Filling adapters for filling vehicle are predominantly designed such that they are clamped onto specifically designed component portions of the vehicle air conditioning system by means of mechanical clamping elements which are operated by means of a pneumatically or mechanically controlled clamping piston. The mechanical clamping elements, which are particularly designed as clamping claws or balls, are kept in the clamped position by the clamping piston. If the control function fails during the filling process or if the clamping piston exercises the control function incorrectly, this will not just impair the filling process but also drop the filling adapter from the respective vehicle interface. Such a drop will be additionally accelerated by the kinetic energy from the filling system.
Based on legal requirements, vehicle air conditioning systems increasingly use refrigerants that meet environmentally friendly requirements. This includes CO2, which as a refrigerant is named R744. Filling with refrigerant R744 is performed at typical pressures between 80 bar and 120 bar. At these pressures, secure clamping of the filling adapter during the filling process is an essential safety requirement to protect the workers in the surrounding area. At the typically high pressure range mentioned, a very great counterforce occurs which must be absorbed by the adapter clamping system. If this is not ensured, there may be leaks in the filling process or even complete loss of the adapter clamping, which is a high safety risk for a worker who operates the filling system or performs operations in the engine compartment of the vehicle to be filled.
Such risks for workers can be reduced or largely be avoided by designing the clamping system to be safe with respect to the system pressure. There is the option to lock the clamping piston in its clamped position (locking) and to monitor the locking element with a sensor. But this has an adverse influence on the size and weight of the clamping system. It should be noted in this respect that the worker who operates the system frequently transports and adapts the filling adapter between the filling system and the vehicle (often after 80 seconds, respectively). A bigger size of the filling system due to a clamping piston locking unit and/or a clamping piston monitoring unit will have a negative impact on ergonomics and work load and also exerts strain on the vehicle ports. This is a considerable disadvantage or even an exclusion criterion for these solutions. The technical complexity of the control system inevitably increases as well.
It is the problem of the invention to create a technical solution with which the locking mechanism of a mechanical clamping system can be durably locked for filling with refrigerant R744 in case the filling valve or the vehicle valve are not closed or if the control pressure drops below a predetermined value.
This problem is solved by applying two different pressure media to the clamping piston, wherein initially the control pressure of the filling adapter is applied, followed by the additional application of the refrigerant filling pressure. A filling adapter is suitable for this in which the clamping piston comprises at least two separate piston surfaces for pressure application by different pressure media, wherein the one piston surface is brought into an operative connection with the control pressure of the filling adapter and the other piston surface is brought into an operative connection with the filling pressure of the refrigerant. Advantageous embodiments are the subject matter of respective dependent claims, whose technical features will be explained in more detail based on an exemplary embodiment.
The technical solution of the invention makes it possible to improve aspects of operator safety and at the same time provide improved functional reliability of a clamping system for filling vehicle air conditioning systems. The clamping system modified accordingly first allows risk-free and safe connecting to the vehicle system and then safe filling at pressures characteristic of the refrigerant R744.
The clamping principle is executed such that the clamping piston is additionally tightened using the pressure of the refrigerant R744 as the filling medium. It only becomes possible to loosen the clamping system and disconnect it from the vehicle system if the system pressure falls below a limit that is non-critical for the safety of the system operator.
The clamping system can thus be designed such that the volume and therefore the weight of the entire filling adapter are kept low due to the combined application of system pressure and filling pressure. This means that the vehicle ports suffer little mechanical strain and acceptable handling of the system by the worker is achieved.